Mayor Ed Lee held a commanding lead in the mayor’s race against a diverse slate of 15 candidates, but because he didn’t garner a majority in Tuesday’s election the city’s instant runoff system has kicked in.

Lee, a former city administrator who replaced then-Mayor Gavin Newsom when he became lieutenant governor in January, was ahead with nearly 31 percent of the vote. City Supervisor John Avalos followed with nearly 18 percent; and City Attorney Dennis Herrera was trailing with 11 percent.

But even with all the precincts counted late Tuesday, it will be at least Wednesday before the city’s 468,000 registered voters know the winner because a voter-approved election system requires that the winner get 50 percent plus one vote. Since Lee didn’t claim more than half the vote, a system in which voters rank their top three candidates will decide the winner.

Still, Lee was jubilant outside his campaign party Tuesday night.

“I worked so hard to make sure that we continue with the success this city knows so well,” said Lee, who would become the city’s first elected Asian-American mayor. “I’m going to work tomorrow, tired or not, because this city is worth the sacrifice.”

Lee’s formal election or that of any of the several other Asian-American candidates on the ballot would symbolize a milestone for the city’s Asians, who make up a third of the population but have traditionally been underrepresented.

Other contenders for the distinction of becoming the city’s first Asian-American mayor included Democratic State Sen. Leland Yee, Adachi and Board of Supervisor President David Chiu. None broke out of single-digit percentages, however.

Caleb Ng, a Chinese-American who voted at City Hall, said he didn’t cast his ballot based on ethnicity.

“It’s not about race; it’s about who can best do the job,” he said.

District Attorney, Sheriff Results

It appeared the city’s other top elected positions — district attorney and sheriff — would also be decided by the ranked-choice voting system.

Former police chief George Gascon was winning his bid to keep his seat as district attorney with more than 44 percent of the vote. David Onek, former head of the San Francisco Police Commission, was trailing with 23 percent.

Longtime Sheriff Michael Hennessey is retiring after three decades of wearing the badge and City Supervisor Ross Mirkarimi was leading the race with 38 percent of the vote.

State Watches SF’s Pension Reform Propositions

With California municipalities watching closely, San Francisco voters showed strong support for a measure to overhaul the city’s pension plan for local government and public safety workers.

More than two-thirds of the voters in Tuesday’s election supported Proposition C, which would increase contributions by workers and raise the minimum retirement age for some to save $1.3 billion over the next decade.

Proposition D, a competing measure that would extend the retirement age even further to save $1.7 billion, was losing by roughly the same two-to-one margin.

Proposition C was supported by Mayor Ed Lee. Other support came from the city’s supervisors, business groups and the public employee unions. Proposition D was opposed by the unions and backed by public defender and mayoral candidate Jeff Adachi.

Pension reform is an issue in cities throughout California as cities struggle to meet the financial commitments to their retirees. San Francisco faces a $4 billion obligation over the next decade for tens of thousands of current and former employees under its current system.

The city’s 2009 civil grand jury study of the system said the “pension and health benefits enjoyed by San Francisco retirees are unsustainable.” The economic downturn hit the pension fund hard and required the city to increase its payments to meet its legal obligation to its retired workers.

Yet the plan also has been seen as too generous, especially in a down economy. At the time of the grand jury’s report, San Francisco had a list of 900 retirees receiving more than $100,000 a year.

Recent examples that have driven the need for reform home are a transit operator, who earned $105,000 annually under the plan, and a nursing supervisor who retired with $202,000 a year and former Police Chief Heather Fong, who retired at 53 with $264,000 per year in yearly benefits.

In addition to requiring employees to pay more, both new plans would change some retirement ages and the years of service needed to qualify for benefits for police, firefighters and other city employees.

Supporters of Proposition C described it as a consensus measure endorsed by diametrically opposed groups — business and labor unions — to achieve real, if not dramatic, savings.

They argued that Proposition D would be ineffective because it would be held up by legal challenges because it lacks a requirement for employee contributions to be reduced if the pension fund recovers.